The Resistance of Germinating Pea (Pisum sativum L.) Seeds to Silver Nanoparticles

The results of our recent research revealed that biologically synthesized silver nanoparticles (bio-AgNPs) applied to several-day-old pea (Pisum sativum L.) plants or used for seed nanopriming protected pea plants against selected fungal pathogens. However, the susceptibility of pea to bio-AgNPs during seed germination remains mostly unknown. Therefore, in this study, we investigated the cells' viability, ROS generation, total antioxidant capacity, the activity of selected antioxidant enzymes, and changes in the polar metabolite profiles of 4-day-old pea seedlings developed in water (control) and water suspensions of bio-AgNPs (at 50 and 200 mg/L). The bio-AgNPs did not negatively affect pea seeds' germination, early seedlings' growth, and root tips cells' viability (at both tested concentrations). In the root, the bio-AgNPs at a lower concentration (50 mg/L) stimulated ROS generation. Nanoparticles enhanced peroxidase activity in root and the total antioxidant capacity in epicotyl. Increased levels of malate, phosphoric acid, proline, GABA, and alanine were observed in root and epicotyl of pea seedlings developed at 50 mg/L of bio-AgNPs. A higher concentration affected the tricarboxylic acid cycle and nitrogen metabolism. Bio-AgNPs alerted oxidative homeostasis and primary metabolism of pea seedlings but did not exceed a certain threshold limit and thus did not injure pea at an early stage of seedling development.